Third day of heatwave prompts Flex Alert conservation call today

September 7, 2020


Consumers reducing energy use instrumental in averting power outages

FOLSOM, Calif. – The California Independent System Operator (ISO) issued a statewide Flex Alert, a call for Californians to conserve electricity today, from 3 p.m. to 9 p.m.

Temperatures are expected to be above normal statewide for the third consecutive day, driving up electricity demand, primarily from air conditioning use.

The ISO is also monitoring several serious wildfires throughout the state threatening power lines. Weather forecasts show wind will pick up beginning late tonight through Wednesday, increasing fire danger. Wildfires can trip or destroy power lines, reducing transmission and shrinking energy supplies.

Consumers can actively help stretch electricity supplies by shifting energy use to morning and nighttime hours. Conservation can lower demand and avoid further actions, including outages, and lessen the duration of power interruptions.

Consumer conservation efforts during a heat wave on Aug. 17 and 18 were key to preventing power outages, and again on Sept. 5 and 6.

The grid operator declared a Stage 2 Emergency just before 6 p.m. Sunday when a transmission line from Oregon reduced capacity by 900 megawatts (MW) due to the heat. At the same time, generation totaling 260 megawatts (MW) tripped offline.

Conservation helped grid operators overcome those challenges and avoid rotating power outages.

Consumers are urged to conserve electricity when the grid is most stressed in the afternoons and evenings, when temperatures remain high and solar production is falling due to the sun setting.

Between 3 p.m. and 9 p.m., the ISO is urging consumers to:

  • Set air conditioning thermostats to 78 degrees, if health permits.
  • Defer use of major appliances.
  • Turn off unnecessary lights.
  • Unplug unused electrical devices.
  • Close blinds and drapes.
  • Use fans when possible.
  • Limit time the refrigerator door is open.

Consumers can also take steps to prepare for the Flex Alert by doing the following before 3 p.m.:

  • "Pre-cool" their homes, or lower air conditioning thermostats.
  • Charge electric vehicles.
  • Charge mobile devices and laptops.
  • Run dishwashers, washing machines and other major appliances.
  • Set pool pumps to run in the early morning or late at night.

For information on Flex Alerts, to get more electricity conservation tips, and to sign up for conservation alerts, visit the ISO's Flex Alert website. Visit the ISO's News page for more information on the heat wave's impacts on grid operations, and to learn more about alerts, warnings and emergency notices.

For updates on grid operations, follow us on Twitter at @California_ISO or @FlexAlert, or monitor system conditions in real time at ISO's Today's Outlook.

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A Flex Alert is issued by the ISO when the electricity grid is under stress because of generation or transmission outages, or from persistent hot temperatures. Glossary of terms and acronyms

Click here to learn more about System Alerts, Warnings and Emergencies. Follow grid conditions in real time at ISO’s Today’s Outlook, or download the free ISO Today mobile app.

This advisory is based on the best data available at the time of its release. Grid conditions can change rapidly and are
subject to change without warning. This forecast is accepted by the recipient on the condition that errors, omissions
and/or changes to the contents shall not be made the basis for any claim, demand or cause of action against the California ISO.